It is well known that bladder dysfunction is associated with a number of clinical conditions requiring treatment. In many of these cases it is important to accurately determine the volume of the bladder. Under other conditions such as post-operative recovery, where there is temporary loss of bladder sensation and/or loss of the normal voiding mechanism too much distention of the bladder has to be avoided. Under those conditions voiding by catheter introduction is carried out. However, serious disadvantages to unnecessary catheterization range from the uncomfortable situation for the patient to serious possibilities of infection. Thus, a non-invasive quick measurement of bladder volume, with the patient usually in the supine position, is indicated. Sometimes the accurate determination of volume is indicated; sometimes however an indication is sufficient. Questions that may be asked are for instance: after voiding: “is there still too much urine left?”; or after surgery “is the bladder filling above a certain level so that voiding is necessary?”
Non-invasive procedures for bladder volume estimation are known, but are either unreliable or expensive or have some other significant disadvantages. Palpation and auscultatory percussion are known to be unreliable, while radiography and dye-excretion techniques are known to be similarly inaccurate. For assessing bladder volume, catheterization remains the “gold standard”. However, it is invasive, painful and might produce traumas or infections.